Fretz C J, Elizondo G, Weissleder R, Hahn P F, Stark D D, Ferrucci J T
Department of Radiology, Massachusetts General Hospital, Boston.
Radiology. 1989 Aug;172(2):393-7. doi: 10.1148/radiology.172.2.2748820.
The effects of magnetic resonance (MR) pulse sequences and timing parameters on tumor-liver contrast were studied in an animal model of metastatic liver cancer. Six spin-echo (SE), three inversion-recovery (IR), and four gradient-echo (GRE) sequences were evaluated at 0.6 T before and after injection of super-paramagnetic iron oxide. GRE techniques, irrespective of echo time and flip angle, showed the greatest change in signal intensity (enhancement) of the liver after administration of iron oxide. Single-acquisition GRE sequences (16 seconds) matched the contrast-to-noise ratio (C/N) performance of the most effective 6.4-minute SE sequences. Multiexcitation GRE sequences showed tumor-liver C/Ns per unit time that were significantly (P less than .05) higher than those achieved with SE and IR sequences. GRE sequences, which recruit intravoxel dephasing as an additional source of transverse relaxation enhancement (T2*), show a higher C/N per unit time and in this respect seem superior to SE and IR sequences for MR imaging with superparamagnetic iron oxide.
在转移性肝癌动物模型中，研究了磁共振（MR）脉冲序列和时间参数对肿瘤-肝脏对比度的影响。在注射超顺磁性氧化铁之前和之后，于0.6 T场强下评估了六种自旋回波（SE）序列、三种反转恢复（IR）序列和四种梯度回波（GRE）序列。无论回波时间和翻转角如何，GRE技术在注射氧化铁后肝脏信号强度（增强）变化最大。单次采集GRE序列（16秒）的对比噪声比（C/N）性能与最有效的6.4分钟SE序列相当。多激发GRE序列每单位时间的肿瘤-肝脏C/N显著高于SE和IR序列（P<0.05）。GRE序列利用体素内失相作为横向弛豫增强（T*2）的额外来源，每单位时间显示出更高的C/N，在这方面，对于使用超顺磁性氧化铁的MR成像而言，似乎优于SE和IR序列。
